The spring brake actuators are divided into two groups; one of which is the diaphragm-diaphragm spring brake actuator and the other is the diaphragm-piston spring brake actuator. The spring brake actuator with internal ventilation subject to the invention is related to the diaphragm-diaphragm type spring brake actuator.
The spring brake actuator is used in pressurized air brake systems present in the heavy commercial vehicles such as trucks, trailers, lorries and busses and said actuator converts the energy stored in the emergency spring into the energy that actuates the brake.
The spring brake actuators comprise an emergency chamber, which is used in the case—there is an air leakage or air is discharged (hand brake is pulled); and a service chamber which is usually engaged under normal driving conditions.
If the vehicle is desired to be stopped or slowed down the service part is used and when the vehicle is fixed the emergency part is used.
In other words, the service chamber functions when the foot brake is actuated and the parking chamber functions when the hand brake of the vehicle is actuated.
The Emergency spring is compressed by means of the air sent to the emergency chamber which is between the emergency diaphragm and the emergency body. This spring is released as soon as the air inside the emergency chamber is discharged and the force required for braking is provided.
Breather holes are present at the emergency body in order to decrease the effect of the air compressed or expanded in the emergency spring section during the up and down movement of the emergency diaphragm of the traditional diaphragm-diaphragm spring brake actuator. Air is discharged to the external environment from the emergency spring section by means of the breather holes, during the down movement of the emergency diaphragm of the diaphragm-diaphragm spring brake actuators. And, air is sucked into the emergency spring section from the external environment by means of the breather holes, during the up movement of the emergency diaphragm. The entry of large particles from the external environment into the emergency spring section is prevented by means of the release bolt plug.
Dust and humidity may enter the emergency spring section by means of the breather holes, during the up motion of the diaphragm. Humidity especially leads to the corrosion of the emergency spring. At the same time, water, dust and mud can enter from such breather holes, and may lead to the untimely damage of the emergency spring, which is used to keep the vehicle parked, due to corrosion. In such a case, the spring brake actuator, which is very important for vehicles, needs to be immediately repaired or changed.
For this reason, in the known state of the art, brake actuator must be mounted such that breathing holes are facing the road, in order to minimize the amount of water, dust and mud entering the emergency spring section and in order to discharge the water and dirt that has entered into the brake actuator, via the breather holes. Otherwise, the water, dirt and humidity that has entered cannot be discharged and this may lead to the corrosion or breakage of the emergency spring. For this reason, in all of the various known mounting types of the brake actuators, it is required that at least four breather holes are drilled with 90° intervals on the emergency body, during production. All these breather holes are closed with plugs and during installation, the breather hole plug of the brake actuator, at the side facing the road must be dismantled. During this procedure, frequently faced problem is that the wrong plug of the breather hole gets dismantled. In such a case, all of the water, dirt that has entered into the emergency spring section from the open breather hole, may not be completely discharged and the emergency spring starts to erode and cannot function properly after being subjected to corrosion. In the same way, it is also possible for the abrasion of the emergency spring to increase if the breather hole plugs that need to be closed are opened due to vibration and environmental conditions.
In the known state of the art, the release bolt plug prevents the entry of foreign matter into the brake actuator from the external environment. The abrasive materials that enter into the brake actuator from the external environment, cause the release bolt plug produced from rubber to erode in time or come off. This situation negatively effects the operation of the emergency spring and leads to the increase of abrasive factors that enter into the spring.
The patent documents WO 2012/164587 A2, CN202100636 U, GB1237641 A are the known state of the art, and are related to an internal ventilation systems of the diaphragm-piston type emergency spring brake actuators. The high pressure and the vacuum pressure that occur inside the emergency spring section in such internal ventilating systems are carried out by a single valve mounted inside the piston pipe plug.
In the U.S. Pat. No. 7,121,191 B1 patent application the internal ventilation system of diaphragm-diaphragm type emergency spring brake actuators are described. The high pressure and the vacuum pressure that occurs inside the emergency spring section, is regulated by means of valve design mounted inside the intermediate shaft flange, sucking air from the service chamber and the passage of the air to the service chamber.
In all of the patent documents WO 2012/164587 A2, CN202100636 U, GB1237641 A and U.S. Pat. No. 7,121,191 shared in relation to the known state of the art above, as the discharging of the high pressure that occurs inside the emergency spring section, to the service chamber and the balancing of the vacuum pressure that occurs inside the emergency spring section, by means of the air that is sucked from the service chamber is carried out by a single valve system; in order to discharge the high pressurized air from the emergency spring section to the service chamber from the valve, the service chamber should not be filled with pressurized air; in other words force should not be applied to the foot brake. In short, when the vehicle is desired to be moved from the parking position to the driving position, the emergency spring cannot be set without removing the force applied to the foot brake and this is a disadvantage. In our invention however, as the discharging of the pressurized air from the emergency spring section and the balancing of the vacuum pressure inside the emergency spring section by means of the air sucked from the service chamber are carried out with different members; the pressurized air is discharged to the atmosphere via a release bolt plug, independent from the pressure located inside the service chamber. In other words, setting of the emergency spring and ensuring that the emergency chamber is ready for braking is carried out rapidly, being independent of the force applied to the foot brake and independent of the pressure located inside the service chamber.
The means subject to the invention and the operation principle of the system subject to the invention differ from each other.